An unpaid intern in Democratic Sen. Bob Menendez's office was arrested Thursday for immigration violations, the New Jersey senator confirmed on MSNBC.

Luis Abrahan Sanchez Zavaleta, an 18-year-old from Peru, was a registered sex offender and was arrested at his home in New Jersey, according to the Associated Press, which first reported the news. Zavaleta does not appear in New Jersey's online sex offender registry.

"Once it came to our attention our New Jersey staff director let the young man go from the program," Menendez said.

"We know that we have a non-paying college intern program, this young man applied to that process, got recommended by the school, we asked status of all of those college interns. Didn't indicate anything about his status," he added. "And we certainly wouldn't have known through any background checks since he is a minor about any sex offender status."